It has become common practice to treat various problems of the middle ear by providing some means of continuously aerating the middle ear through the tympanic membrane. This has been accomplished by inserting ventilation tubes through the tympanic membrane or through a bony area adjacent thereto. Various ventilation and drain tubes which have been previously proposed are shown in U.S. Pat. Nos. 3,530,860; 3,807,409; 3,871,380; 3,916,873; 3,948,271; 3,982,454 and 3,976,081. These prior art ventilation tubes are each subject to one or more serious defects which it is the object of the present invention to overcome.
More particularly, one of the principal defects of the prior art ventilation tubes is that they do not effectively seal off the inner ear from the entrance of water. If water enters the inner ear through such a tube, it can lead to aggravated middle ear infection. As a consequence, patients who have heretofore been fitted with inner ear ventilation tubes have been restricted in their activities, particularly those involving water. Thus, such patients could not normally go swimming.
A still further difficulty with prior art ventilation tubes is that they provided no ready means for changing the filter element. For example, if a tube has been in place for a substantial length of time, the tympanic membrane may tend to grow into the tube. With prior art ventilation tubes, it was necessary to replace the entire tube which consumed a substantial amount of time and entails considerable discomfort to the patient.